Typically an LED driver is designed in a BUCK or Boost circuit topology, but such a circuit design is relatively complex, and involves severe electromagnetic interference. Another solution relates to the use of a non-polar capacitor coupled with an alternating-current power supply. However the non-polar capacitor suffers from small capacitance and low driving power due to the limitation of its process and has to be produced with a large size for a better driving effect, thus resulting in a bulky driver which occupies a considerable space and is produced at an increased cost.